This invention relates to a disk information recording medium. More particularly, the present invention relates to an information recording disk, which limits the eccentric distance between the center position of a positioning signal for an information convertor and the center position of rotation of an information recording disk and is suitable for positioning highly accurately and at a high speed the information convertor, to its production method and to an information recording apparatus using the information recording disk.
When information is recorded or reproduced by positioning a rotary magnetic disk and a radially moving information convertor, the information convertor must be positioned highly accurately to a desired information track. The positioning method of the information convertor has changed from an early open loop method to a closed loop servo method using a positioning signal. To obtain still higher accuracy, attempts have been made, recently, to dispose the positioning signal on the recording track, or very close to it on the surface on which the information is to be recorded and reproduced. The positioning signal is detected by the information convertor itself, or a position reference detector disposed on the information convertor, or very close to it.
In optical disk apparatuses such as a compact disk (CD), for example, tracking grooves are formed on the recording surface and information pits are formed on, or in the proximity of, the grooves. The information convertor is positioned to this tracking groove and records or reproduces the information pit at a predetermined position.
In magnetic disk storage, an apparatus for accomplishing a high track density uses a positioning signal at a predetermined angle position of each recording track, detects this positioning signal by a magnetic head for recording and reproducing the information, and positions the magnetic head to the recording track by use of this detection signal, as disclosed, for example, in Japanese Patent Publication No. 54872/1982.